The epicenter was off the northeastern coast of Japan, about 50 kilometers (31 miles) below the seabed.

A strong 6.3-magnitude earthquake struck in the Pacific off Fukushima, northeastern Japan, on Sunday, but there was no tsunami threat, US and Japanese authorities said. The quake jolted large areas in the region at 7:23 pm (1023 GMT) with its epicentre located 54 kilometres (34 miles) east of Namie, eastern Fukushima, according to the US Geological Survey said. The quake was also felt in Tokyo.

The Japan Meteorological Agency said there were no worries about tsunami damage.The weather agency issued an emergency warning when the quake hit, but there was no immediate report of injuries or damage.

No abnormality was detected at nuclear plants in the region, including the Fukushima Daiichi nuclear power plant, NHK said.

More than 18,000 were killed after a 9.0-magnitude earthquake triggered a massive tsunami on March 11, 2011, leading to the meltdown of reactors at the Fukushima plant.Japan sits at the junction of four tectonic plates and experiences a number of relatively violent quakes every year.